Alkylated Aromatics Production

ABSTRACT

Disclosed is a process for the production of alkylated aromatics by contacting a feed stream comprising an alkylatable aromatic, an alkylating agent and trace amounts of water and impurities in the presence of first and second alkylation catalysts wherein the water and impurities are removed in order to improve the cycle length of such alkylation catalysts. Water and a portion of impurities are removed in a dehydration zone. A first alkylation zone having a first alkylation catalyst which, in some embodiments is a large pore molecular sieve, acts to remove a larger portion of impurities, such as nitrogenous and other species, and to alkylate a smaller portion of the alkylatable aromatic compound. A second alkylation zone, which in some embodiments is a medium pore molecular sieve, acts to remove a smaller portion of impurities, and to alkylate a larger portion of the alkylatable aromatic compound.

FIELD

The present disclosure relates to a process for the production ofalkylated aromatic compounds from a feed stream comprising an alkylatingagent, an alkylatable aromatic and trace amounts of water andimpurities.

BACKGROUND

Alkylated aromatic compounds, such as cumene, ethylbenzene and sec-butylbenzene, are often produced by the liquid phase alkylation reaction ofalkylatable aromatics (e.g., benzene), and alkylating agents (e.g.,olefins such as ethylene, propylene and butylene) in the presence ofacidic molecular sieve catalysts (e.g., zeolites). Liquid phasearomatics alkylation processes often result in reduced operating costsand fewer undesirable byproducts produced (e.g., xylenes) than inearlier vapor phase technologies.

Acidic molecular sieve catalysts that may be used for such liquid phasearomatic alkylation reactions include zeolite beta, zeolite Y, zeoliteomega, ZSM-5, ZSM-12, MCM-22, MCM-36, MCM-49, MCM-56, MCM-58, MCM-68,UZM-8, faujasite, Mordenite, porous crystalline magnesium silicates, andTungstate-modified zirconia (e.g., Zr(WO₄)₂, all of which are known inthe art.

Operation of liquid phase aromatics alkylation reactions especially atrelatively low temperatures has resulted in greater catalyst sensitivityto trace impurities (e.g., “catalyst poisons”) in the alkylatablearomatic or alkylating agent feed streams. Such impurities often resultin more frequent catalyst regeneration requirements and reduced ultimatelife of the catalyst before replacement is necessary. Catalystreplacement often involves a process shutdown, lost production, andsignificant costs. A variety of processes have been developed forpretreating aromatic and/or alkylating agent feed streams to removecatalyst poisons. These processes include distillation, adsorption, andextraction.

U.S. Pat. No. 6,313,362 (Green) teaches an aromatic alkylation processin which the alkylation product is contacted with a large pore molecularsieve catalyst such as MCM-22 in a liquid phase step to removeimpurities prior to liquid phase alkylation. Impurities taught as beingremoved include olefins, diolefins, styrene, oxygenated organiccompounds, sulfur-containing compounds, nitrogen-containing compounds,and oligomeric compounds.

U.S. Pat. No. 4,358,362 (Smith) teaches a method for enhancing catalyticactivity of a zeolite catalyst by contacting a feed stream whichcontains a catalytically deleterious impurity with a zeolitic sorbent.This disclosure uses a sorbent with a Si/Al ratio greater than 12,10-12-membered rings, and a Constraint Index between 1 and 12,preferably ZSM-11.

U.S. Pat. No. 5,030,786 (Shamshoum) teaches a process for production ofethylbenzene in which the catalyst lifetime is increased by reducing theconcentration of water in the feed to the reactor.

U.S. Pat. No. 5,744,686 (Gajda) teaches a process for the removal ofnitrogen compounds from an aromatic hydrocarbon stream by contacting thestream with a selective adsorbent having an average pore size less thanabout 5.5 Angstroms. The selective adsorbent is a non-acidic molecularsieve selected from the group consisting of pore closed zeolite 4A,zeolite 4A, zeolite 5A, silicalite, F-silicalite, ZSM-5, and mixturesthereof.

A process for preparing alkylated benzenes is taught in U.S. Pat. No.6,297,417 (Samson). The process includes contacting a benzene feedstockwith a solid acid, such as acidic clay or acidic zeolite, in apretreatment zone at a temperature between about 130° C. and about 300°C. to improve the lifetime of the alkylation and transalkylationcatalyst.

U.S. Pat. No. 6,355,851 (Wu) teaches a zeolite-catalyzed cumenesynthesis process in which benzene feedstock is contacted with a “hot”clay bed, followed by distillation of the benzene feedstock to separatethe benzene from the higher molecular weight materials formed fromolefinic poisons during the hot clay treatment, followed by a “cold”clay treatment wherein the benzene distillate is contacted with anambient-temperature clay. The propylene feedstock is pretreated bycontact with an alumina to remove trace sodium compounds and moisture, amolecular sieve to remove water, and two modified aluminas to removeother catalyst poisons. The pretreated propylene and benzene feedstocksare then reacted in the presence of a zeolite catalyst to form cumenewithout causing rapid degradation of the catalyst's activity.

PCT published application WO0214240 (Venkat) teaches removal of polarcontaminants in an aromatic feedstock by contacting it with molecularsieves with pore size greater than 5.6 Angstroms at temperatures below130° C.

U.S. Pat. No. 6,894,201 (Schmidt) teaches removing nitrogen compoundsfrom an alkylation substrate such as benzene prior to alkylation using aconventional adsorbent bed which adsorbs basic organic nitrogencompounds and a hot adsorbent bed of acidic molecular sieve whichadsorbs weakly basic nitrogen compounds such as nitrites. Schmidtteaches that water facilitates the adsorption of the weakly basicnitrogen compounds and that running an alkylation substrate stream froma fractionation column of elevated temperature and suitable waterconcentration to the hot adsorbent bed may be advantageous.

U.S. Pat. No. 7,199,275 (Smith) teaches a process for hydrocarbonconversion in which a partially dehydrated hydrocarbon feedstock iscontacted with at least two different molecular sieve materials,including a first molecular sieve having a Si/Al molar ratio of lessthan about 5 and a second molecular sieve having a Si/Al molar ratio ofgreater than about 5. Also, Smith teaches processes in which suchfeedstocks are contacted with a first molecular sieve having pores of atleast about 6 Angstroms and a second molecular sieve having pores ofless than about 6 Angstroms.

These prior references do not provide for the alkylation of a feedstream by contact with an alkylation catalyst, wherein the feed streamcontains an alkylatable aromatic compound, an alkylating agent and traceamounts of water and impurities and a portion of the water andimpurities are removed at the same time as the feed stream is alkylated.The presence of water and impurities in the feed stream negativelyimpact the catalytic activity and cycle length of the alkylationcatalyst in alkylation processes.

Therefore, there is a need for an improved process for the production ofalkylated aromatics by contacting such a feed stream with a first andthen a different second alkylation catalyst to remove a portion of waterand impurities and alkylate a portion of the alkylatable aromatic suchthat the adverse impact on the activity and cycle length on suchalkylation catalyst by water and impurities is mitigated. Thisdisclosure meets this and other needs.

SUMMARY OF THE DISCLOSURE

The present disclosure describes a process for the production ofalkylated aromatic compounds from a feed stream comprising an alkylatingagent, an alkylatable aromatic and trace amounts of water andimpurities. Water, and optionally a portion of impurities, is removed ina dehydration zone. In a reactive guard bed, the dehydrated stream andan alkylating agent are contacted with a first alkylation catalyst, andthen a different second alkylation catalyst, wherein any remainingimpurities are removed at the same time as this stream is alkylated.Alternatively in a non-reactive guard bed, the dehydrated stream iscontacted with a first catalyst wherein any remaining impurities areremoved, and then this stream is alkylated with an alkylating agent bycontact with an alkylation catalyst.

The first alkylation catalyst in the first alkylation zone in someembodiments is a large pore molecular sieve. The second alkylationcatalyst in the second alkylation zone in some embodiments is a mediumpore molecular sieve or a MCM-22 family material.

While not intending to be bound by any theory, it is believed that thedehydration step reduces the concentration of water and optionallyreduces the level of impurities in the alkylatable aromatic feed. Aportion of the impurities are removed at the same time as a portion ofthe water. This enables the first alkylation step to remove a portion,preferably a major portion, of the remaining impurities, such asnitrogenous and other species, contained in the alkylatable aromaticfeed, and to alkylate a portion of the alkylatable aromatic compound.Preferably at least 80%, at least 70% or at least 60% by weight, of theremaining impurities are removed. The second alkylation step in turnacts to remove a portion of the remaining impurities, and to alkylate amajor portion of the alkylatable aromatic compound. Preferably at least80%, at least 70% or at least 60% by weight, of the alkylatable aromaticcompound is alkylated with an alkylating agent.

The alkylated aromatic compounds produced comprise primarilymono-alkylated aromatic compounds with trace amounts of poly-alkylatedaromatic compounds produced concomitantly in the alkylation reactionzones. The poly-alkylated aromatic compounds may then be converted toadditional mono-alkylated compounds by contact with additionalalkylatable aromatic compounds in the presence of a separatetransalkylation catalyst in a transalkylation step.

DESCRIPTION OF THE DRAWINGS

FIGS. 1-8 are each process flow diagrams of a process for producingalkylated aromatic compounds in accordance with an embodiment of thepresent disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Definitions

The term “alkylatable aromatic compound” as used herein means anaromatic compound that may receive an alkyl group. One non-limitingexample of an alkylatable aromatic compound is benzene.

The term “alkylating agent” as used herein means a compound which maydonate an alkyl group to an alkylatable aromatic compound. Non-limitingexamples of an alkylating agent are ethylene, propylene, and butylene.Another non-limiting example is any poly-alkylated aromatic compoundthat is capable of donating an alkyl group to an alkylatable aromaticcompound.

The term “aromatic” as used herein in reference to the alkylatablearomatic compounds which are useful herein is to be understood inaccordance with its art-recognized scope which includes substituted andunsubstituted mono- and polynuclear compounds. Compounds of an aromaticcharacter which possess a heteroatom (e.g., N or S) are also usefulprovided they do not act as catalyst poisons, as defined below, underthe reaction conditions selected.

The term “at least partially liquid phase” as used herein means amixture having at least 1 wt. % liquid phase, optionally at least 5 wt.% liquid phase, at a given temperature, pressure, and composition.

The term “catalyst poison” as used herein means an impurity, definedherein, which acts to reduce the cycle-length of a molecular sieve orzeolite.

The term “cycle length” as used herein means the total on-oil timebetween regenerations, or the on-oil time period between fresh load andregeneration. After the fresh catalyst or the regenerated catalyst beingbrought on-oil, the catalyst may be deactivated due to coke depositionor poison. As the catalyst becomes deactivated, the reaction zone has tobe operated at higher temperatures to maintain the same productivity orcatalytic activity. The catalyst has to be regenerated once the reactionzone temperature reaches a threshold temperature, typically determinedby metallurgy of the reactor or when economic factors warrant.

The term “framework type” is used herein has the meaning described inthe “Atlas of Zeolite Framework Types,” by Ch. Baerlocher, W. M. Meierand D. H. Olson (Elsevier, 5th Ed., 2001.)

The numbering scheme for the elements of the Periodic Table Groups asused herein has the meaning described in the Periodic Table of Elementsas published by International Union of Pure and Applied Chemistry on 22Jun. 2007.

The term “impurities” as used herein includes, but is not limited to,compounds having at least one of the following elements: nitrogen,halogens, oxygen, sulfur, arsenic, selenium, tellurium, phosphorus, andGroup 1 through Group 12 metals.

The impurities content as used in this disclosure means the wppm ofimpurities based on the total weight of the combined alkylatablearomatic compound and alkylating agent in the reaction zone.

The term “MCM-22 family material” (or “material of the MCM-22 family” or“molecular sieve of the MCM-22 family”), as used herein, includes:

(i) molecular sieves made from a common first degree crystallinebuilding block “unit cell having the MWW framework topology.” A unitcell is a spatial arrangement of atoms which is tiled inthree-dimensional space to describe the crystal as described in the“Atlas of Zeolite Framework Types,” by Ch. Baerlocher, W. M. Meier andD. H. Olson (Elsevier, 5th Ed., 2001.);

(ii) molecular sieves made from a common second degree building block, a2-dimensional tiling of such MWW framework type unit cells, forming a“monolayer of one unit cell thickness,” preferably one c-unit cellthickness;

(iii) molecular sieves made from common second degree building blocks,“layers of one or more than one unit cell thickness”, wherein the layerof more than one unit cell thickness is made from stacking, packing, orbinding at least two monolayers of one unit cell thick of unit cellshaving the MWW framework topology. The stacking of such second degreebuilding blocks can be in a regular fashion, an irregular fashion, arandom fashion, and any combination thereof; or

(iv) molecular sieves made by any regular or random 2-dimensional or3-dimensional combination of unit cells having the MWW frameworktopology.

The MCM-22 family materials are characterized by having an X-raydiffraction pattern including d-spacing maxima at 12.4±0.25, 3.57±0.07and 3.42±0.07 Angstroms (either calcined or as-synthesized). The MCM-22family materials may also be characterized by having an X-raydiffraction pattern including d-spacing maxima at 12.4±0.25, 6.9±0.15,3.57±0.07 and 3.42±0.07 Angstroms (either calcined or as-synthesized).The X-ray diffraction data used to characterize the molecular sieve areobtained by standard techniques using the K-alpha doublet of copper asthe incident radiation and a diffractometer equipped with ascintillation counter and associated computer as the collection system.

The term “mono-alkylated aromatic compound” means an aromatic compoundthat has only one alkyl substituent. Non-limiting examples ofmono-alkylated aromatic compounds are ethylbenzene, iso-propylbenzene(cumene) and sec-butylbenzene.

The term “on-oil” as used herein is to be understood as the catalystbeing brought under alkylation or transalkylation conditions. Thealkylation or transalkylation conditions include temperature, pressure,alkylatable aromatic compound(s), alkylating agent(s), and WHSV, whichare suitable to covert at least 1 wt. %, preferably at least 10 wt. % ofthe alkylatable aromatic compound(s) (based on the total alkylatablearomatic compound(s) in the feed) to the mono-alkylated aromaticcompound(s).

The term “poison capacity” as used herein means the millimoles ofcollidine (a catalyst poison) absorbed per gram of a catalyst samplethat is dried under nitrogen flow at 200° C. for 60 minutes on aThermogravametric Analyzer (Model Q5000, manufactured by TA Instruments,New Castle, Del.). After drying, the collidine catalyst poison issparged over the catalyst sample for 60 minutes at a collidine partialpressure of 3 ton. The poison capacity is calculated from the followingformula: (Catalyst Sample Weight after Sparging with collidine−DriedCatalyst Sample Weight)×10⁶÷(Molecular Weight of Collidine×DriedCatalyst Sample Weight). When the Catalyst Sample Weight and the DriedCatalyst Sample Weight is measured in grams, the molecular weight ofcollidine is 121.2 grams per millimole.

The term “poly-alkylated aromatic compound” as used herein means anaromatic compound that has more than one alkyl substituent. Anon-limiting example of a poly-alkylated aromatic compound ispoly-alkylated benzene, e.g., di-ethylbenzene, tri-ethylbenzene,di-isopropylbenzene, and tri-isopropylbenzene.

The term “wppb” as used herein is defined as parts per billion byweight.

The term “wppm” as used herein is defined as parts per million byweight.

Feedstocks and Products

Suitable unsubstituted aromatic compounds that may be used for thisdisclosure include benzene, naphthalene, anthracene, naphthacene,perylene, coronene, and phenanthrene, with benzene being preferred.

Substituted aromatic compounds which may be used for the disclosureshould possess at least one hydrogen atom directly bonded to thearomatic nucleus. The aromatic rings may be substituted with one or morealkyl, aryl, alkaryl, alkoxy, aryloxy, cycloalkyl, halide, and/or othergroups which do not interfere with the alkylation reaction. Generallythe alkyl groups which can be present as substituents on the aromaticcompound contain from 1 to about 22 carbon atoms and usually from about1 to 8 carbon atoms, and most usually from about 1 to 4 carbon atoms.

Suitable substituted aromatic compounds that may be used for thisdisclosure include, but are not limited to, toluene, xylene,isopropylbenzene, normal propylbenzene, alpha-methylnaphthalene,ethylbenzene, mesitylene, durene, cymenes, butylbenzene, pseudocumene,o-diethylbenzene, m-diethylbenzene, p-diethylbenzene, isoamylbenzene,isohexylbenzene, pentaethylbenzene, pentamethylbenzene;1,2,3,4-tetraethylbenzene; 1,2,3,5-tetramethylbenzene;1,2,4-triethylbenzene; 1,2,3-trimethylbenzene, m-butyltoluene;p-butyltoluene; 3,5-diethyltoluene; o-ethyltoluene; p-ethyltoluene;m-propyltoluene; 4-ethyl-m-xylene; dimethylnaphthalenes;ethylnaphthalene; 2,3-dimethylanthracene; 9-ethylanthracene;2-methylanthracene; o-methylanthracene; 9,10-dimethylphenanthrene; and3-methyl-phenanthrene.

Higher molecular weight alkylaromatic hydrocarbons may also be used asstarting materials and include aromatic hydrocarbons such as areproduced by the alkylation of aromatic hydrocarbons with olefinoligomers. Such products are frequently referred to in the art asalkylate and include, but are not limited to, hexylbenzene,nonylbenzene, dodecylbenzene, pentadecylbenzene, hexyltoluene,nonyltoluene, dodecyltoluene, pentadecytoluene, and the like. Very oftenalkylate is obtained as a high boiling fraction in which the alkyl groupattached to the aromatic nucleus varies in size from about C₆ to aboutC₁₆.

Reformate streams that may contain substantial quantities of benzene,toluene and/or xylene may be particularly suitable as an alkylatablearomatic feed for the process of this disclosure. Although the processis particularly directed to the production of ethylbenzene from polymergrade and dilute ethylene, it is equally applicable to the production ofother C₇-C₂₀ alkylaromatic compounds, such as cumene, as well as C₆₊alkylaromatics, such as C₈-C₁₆ linear and near linear alkylbenzenes.

Suitable alkylating agent(s) that may be used in this disclosurecomprise alkene compound(s), alcohol compound(s), and/oralkylbenzene(s), and mixtures thereof. Other suitable alkylating agentsthat may be useful in the process of this disclosure generally include,but are not limited to, any aliphatic or aromatic organic compoundhaving one or more available alkylating aliphatic groups capable ofreaction with the alkylatable aromatic compound. Examples of suitablealkylating agents are C₂-C₁₆ olefins, such as C₂-C₅ olefins, includingethylene, propylene, the butenes, and the pentenes; C₁-C₁₂ alkanols(inclusive of monoalcohols, dialcohols, trialcohols, etc.), preferablyC₁-C₅ alkanols, such as methanol, ethanol, the propanols, the butanols,and the pentanols; C₂-C₂₀ ethers, e.g., C₂-C₅ ethers includingdimethylether and diethylether; aldehydes such as formaldehyde,acetaldehyde, propionaldehyde, butyraldehyde, and n-valeraldehyde; andalkyl halides such as methyl chloride, ethyl chloride, the propylchlorides, the butyl chlorides, and the pentyl chlorides, polyalkylatedaromatic compound(s), e.g., bi-alkylated benzenes (e.g.,bi-ethylbenzene(s) or bi-isopropylbenzenes) and tri-alkylated benzene(s)(e.g., tri-ethylbenzenes or tri-isopropylbenzenes), and so forth. Thusthe alkylating agent may preferably be selected from the groupconsisting of C₂-C₅ olefins, C₁-C₅ alkanols, bi-ethylbenzene(s),isopropylbenzene(s), tri-ethylbenzene(s) and/or tri-isopropylbenzene(s).

Impurities

In this disclosure, the feed stream comprising the alkylatable aromaticcompound may comprise impurities. Optionally, the first alkylating agentstream and/or the second alkylating agent stream may compriseimpurities. The impurities comprise a compound having at least one ofthe following elements: nitrogen, halogens, oxygen, sulfur, arsenic,selenium, tellurium, phosphorus, and Group 1 through Group 12 metals.Examples of such impurities include collidine and N-formyl morpholine.For the purposes of this disclosure, the term “impurities” does notinclude water, H₂O.

In some embodiments, the amount of said impurities in said feed stream(or the first and/or the second alkylating agent stream) is less than 20wppm, less than 15 wppm, less than 10 wppm, less than 5 wppm or lessthan 1 wppm based on the weight of said feed stream.

Water Content

In one or more embodiments, the feed stream may comprise water.Optionally, the first alkylating agent stream and/or the secondalkylating agent stream may comprise water. The feed stream or thealkylating agent stream(s) may be dehydrated by distillation,adsorption, evaporation, extraction or flashing, for example, in one ormore dehydration zones. The dehydration zone may be a distillationcolumn, a benzene column or a flashing column, lights column or anextractor, absorber or flash drum.

In some embodiments, the feed stream is saturated with water at thetemperature and pressure conditions of the feed stream. In otherembodiments, the amount of water in said feed stream is at least 500wppm, at least 400 wppm, at least 300 wppm or at least 200 wppm based onthe weight of said feed stream.

The level of impurities or water may be measured by conventionaltechniques, such as, GC, GC/MS, or other suitable techniques known toone skilled in the art.

Reaction Conditions

The disclosed process includes: (1) a dehydration zone operated undersuitable dehydration conditions to remove at least a portion of waterand optionally, a portion of the impurities; (2) a first alkylationreaction zone having a first alkylation catalyst, wherein the firstalkylation zone is operated under suitable first reaction conditions toremove a major portion of remaining impurities and to alkylate a portionof the alkylatable aromatic compound; (3) a second alkylation reactionzone having a second alkylation catalyst which is different from thefirst alkylation catalyst, wherein the second alkylation zone isoperated under suitable second reaction conditions to remove a portionof remaining impurities and alkylate a major portion of the alkylatablearomatic to produce an additional amount of mono-alkylated aromaticcompounds.

In the dehydration zone, the suitable dehydration conditions areconventional dehydration conditions known in the art to separate waterand impurities from an aromatic stream.

In the first alkylation reaction zone and/or second alkylation reactionzone, when an alkylatable aromatic compound and an alkylating agent arecontacted under conditions of at least partially liquid phase, suitablefirst and second conditions, respectively, include a temperature of 100to 285° C., preferably, a temperature from 150 to 260° C.; a pressure of689 to 4601 kPa-a, preferably, a pressure of 1500 to 3000 kPa-a; and aWHSV based on both alkylating agent and alkylatable aromatics for theoverall reactor of 10 to 100 hr⁻¹, preferably, 20 to 50 hr⁻¹. Theoverall molar ratio of the alkylatable aromatic compound to thealkylating agent (e.g., benzene and ethylene, respectively) ranges from1:1 to 10:1, 2:1 to 8:1, 3:1 to 7:1, or 1.5:1 to 4.5:1.

In some embodiments, the first alkylation reaction zone may be operatedas a reactive guard bed in which at least a portion of impurities in thefeed stream are removed. In this embodiment, the overall molar ratio ofthe alkylatable aromatic compound to the alkylating agent (e.g., benzeneand ethylene, respectfully) is much higher than in alkylation servicealone, in the range from 10:1 to 200:1, or 15:1 to 150:1, or 20:1 to100:1 or 25:1 to 50:1.

In other embodiments, the first reaction alkylation zone is a firstreaction zone operated as a non-reactive guard bed in which at least aportion of impurities in the feed stream are removed. In thisembodiment, only the alkylatable aromatic compound is fed to the firstreaction zone.

In some embodiments, the disclosed process includes a treatment zonehaving a treatment material, wherein the treatment zone is operatedunder suitable treatment conditions to remove a portion of impurities.The treatment zone may be upstream or downstream of the dehydrationzone. The treatment zone is upstream of the first and second alkylationzones.

When a treatment material is used to remove a portion of impurities,suitable treatment conditions include a temperature from about 30 to200° C., and preferably between about 60 to 150° C., a weight hourlyspace velocity (WHSV) of from about 0.1 hr⁻¹ and about 200 hr⁻¹,preferably from about 0.5 hr⁻¹ to about 100 hr⁻¹, and more preferablyfrom about 1.0 hr⁻¹ to about 50 hr⁻¹; and a pressure between aboutambient and 3000 kPa-a.

In some embodiments, the disclosed process includes a transalkylationzone operated under suitable transalkylation conditions to produceadditional amounts of mono-alkylated aromatic compounds frompoly-alkylated aromatic compounds and the alkylatable aromatic compound.

In the transalkylation zone, when poly-alkylated aromatic compounds(e.g., polyethylbenzene(s) or polyisopropylbenzene(s) are contacted withalkylatable aromatic compound under at least partially liquid phaseconditions, suitable transalkylation conditions may include atemperature of from about 100 to about 300° C., a pressure of 696 to4137 kPa-a (101 to 600 psia), a WHSV based on the weight of thepolyalkylated aromatic compound(s) feed to the alkylation reaction zoneof from about 0.5 hr⁻¹ to about 100 hr⁻¹ and a molar ratio of benzene topolyalkylated aromatic compound(s) of from 1:1 to 30:1, preferably, 1:1to 10:1, more preferably, 1:1 to 5:1.

Catalysts

The disclosed process includes: (1) a first alkylation catalyst; and (2)a second alkylation catalyst that is different from the first alkylationcatalyst.

The first alkylation catalyst comprises a large pore molecular sievehaving a Constraint Index of less than 2 and a first poison capacity.

The Constraint Index is a convenient measure of the extent to which analuminosilicate or molecular sieve provides controlled access tomolecules of varying sizes to its internal structure. For example,aluminosilicates which provide a highly restricted access to and egressfrom its internal structure have a high value for the Constraint Index,and aluminosilicates of this kind usually have pores of small size, e.g.less than 5 Angstroms. On the other hand, aluminosilicates which providerelatively free access to the internal aluminosilicate structure have alow value for the constraint index, and usually pores of large size. Themethod by which Constraint Index may be determined is described fully inU.S. Pat. No. 4,016,218.

Suitable large pore molecular sieves include zeolite beta, zeolite Y,Ultrastable Y (USY), Dealuminized Y (Deal Y), Ultrahydrophobic Y(UHP-Y), Rare earth exchanged Y (REY), mordenite, TEA-mordenite, ZSM-3,ZSM-4, ZSM-14, ZSM-18, and ZSM-20. Zeolite ZSM-14 is described in U.S.Pat. No. 3,923,636. Zeolite ZSM-20 is described in U.S. Pat. No.3,972,983. Zeolite beta is described in U.S. Pat. No. 3,308,069, andU.S. Reissue Pat. No. 28,341. Low sodium Ultrastable Y molecular sieve(USY) is described in U.S. Pat. Nos. 3,293,192 and 3,449,070.Dealuminized Y zeolite (Deal Y) may be prepared by the method found inU.S. Pat. No. 3,442,795. Ultrahydrophobic Y (UHP-Y) is described in U.S.Pat. No. 4,401,556. Rare earth exchanged Y (REY) is described in U.S.Pat. No. 3,524,820. Mordenite is a naturally occurring material but isalso available in synthetic forms, such as TEA-mordenite (i.e.,synthetic mordenite prepared from a reaction mixture comprising atetraethylammonium directing agent). TEA-mordenite is disclosed in U.S.Pat. Nos. 3,766,093 and 3,894,104.

The zeolitic materials designated by the International ZeoliteAssociation Structure Committee (TZA-SC) as being of the MWW topologyare multi-layered materials which have two pore systems arising from thepresence of both 10 and 12 membered rings. The Atlas of ZeoliteFramework Types currently classes at least five differently namedmaterials as having this same topology include, but are not limited toMCM-22, ERB-1, ITQ-1, PSH-3, and SSZ-25.

In some embodiments, the second alkylation catalyst, preferably anacidic catalyst, comprises a MCM-22 family molecular sieve having asecond poison capacity. The MCM-22 family molecular sieves have beenfound to be useful in a variety of hydrocarbon conversion processes.Examples of MCM-22 family molecular sieve are MCM-22, MCM-36, MCM-49,MCM-56, ITQ-1, ITQ-2, ITQ-30, PSH-3, SSZ-25, ERB-1 and UZM-8.

Materials which belong to the MCM-22 family include MCM-22 (described inU.S. Pat. No. 4,954,325), PSH-3 (described in U.S. Pat. No. 4,439,409),SSZ-25 (described in U.S. Pat. No. 4,826,667), ERB-1 (described inEuropean Patent 0293032), ITQ-1 (described in U.S. Pat. No. 6,077,498),ITQ-2 (described in International Patent Publication No. WO97/17290),ITQ-30 (described in International Patent Publication No. WO2005118476),MCM-36 (described in U.S. Pat. No. 5,250,277), MCM-49 (described in U.S.Pat. No. 5,236,575), MCM-56 (described in U.S. Pat. No. 5,362,697), andUZM-8 (described in U.S. Pat. No. 6,756,030).

It is to be appreciated that the MCM-22 family molecular sievesdescribed above are distinguished from conventional large pore zeolitealkylation catalysts, discussed below, such as mordenite, in that theMCM-22 materials have 12-ring surface pockets which do not communicatewith the 10-ring internal pore system of the molecular sieve.

Alternatively, the second alkylation catalyst, preferably an acidiccatalyst, may comprise a medium pore molecular sieve having a ConstraintIndex of 2-12 (as defined in U.S. Pat. No. 4,016,218), including ZSM-5,ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35, and ZSM-48. ZSM-5 is describedin detail in U.S. Pat. No. 3,702,886 and U.S. Pat. Reissue No. 29,948.ZSM-11 is described in detail in U.S. Pat. No. 3,709,979. ZSM-12 isdescribed in U.S. Pat. No. 3,832,449. ZSM-22 is described in U.S. Pat.No. 4,556,477. ZSM-23 is described in U.S. Pat. No. 4,076,842. ZSM-35 isdescribed in U.S. Pat. No. 4,016,245. ZSM-48 is more particularlydescribed in U.S. Pat. No. 4,234,231.

In one or more embodiments, said first poison capacity of said firstalkylation catalyst is greater than said second poison capacity of saidsecond alkylation catalyst, said poison capacity measured by collidinecapacity.

In some embodiments, the disclosed process includes a treatmentmaterial. The treatment material is selected from the group consistingof clay, resin, Linde type X, Linde type A, and combinations thereof.The treatment material may be acidic or non-acidic.

In some embodiments, the disclosed process includes a transalkylationcatalyst. The transalkylation catalyst comprises a large pore molecularsieve having a Constraint Index of less than 2. The transalkylationcatalyst may be the same as or different from the first alkylationcatalyst.

Detail Description of the Process

In operation of one embodiment (e.g., reactive guard bed), the processfor producing alkylated aromatic compounds, for example mono-alkylatedand poly-alkylated aromatic compounds, such process comprises the stepsof: (a) supplying a feed stream to a dehydration zone, said feed streamcomprising an alkylatable aromatic compound, water, and impurities,wherein said impurities comprise a compound having at least one of thefollowing elements: nitrogen, halogens, oxygen, sulfur, arsenic,selenium, tellurium, phosphorus, and Group 1 through Group 12 metals;(b) removing at least a portion of said water from said feed stream insaid dehydration zone to produce a dehydrated stream comprising saidalkylatable aromatic compound, any remaining water, and said impurities;(c) contacting at least a portion of said dehydrated stream and a firstalkylating agent stream with a first alkylation catalyst having a firstpoison capacity in a first alkylation reaction zone under suitable atleast partially liquid phase first reaction conditions to remove atleast a portion of said impurities, and to alkylate a portion of saidalkylatable aromatic compound with said first alkylating agent stream,and produce a first alkylated stream comprising alkylated aromaticcompound(s) (e.g., mono-alkylated and polyalkylated aromatic compounds),unreacted alkylatable aromatic compound, any remaining water, and anyremaining impurities, preferably, wherein said remaining impurities arereduced by at least 25% as compared to said impurities in saiddehydrated stream; and (d) contacting said first alkylated stream and asecond alkylating agent stream with a second alkylation catalystdifferent from said first alkylation catalyst, said second alkylationcatalyst having a second poison capacity, in a second alkylationreaction zone under suitable at least partially liquid phase secondreaction conditions to alkylate at least a portion of said unreactedalkylatable aromatic compound with said second alkylating agent streamand produce a second alkylated stream comprising additional saidalkylated aromatic compound(s), unreacted alkylatable aromatic compound,any remaining water, and any remaining impurities.

In the reactive guard bed, a portion of the reactive impurities (e.g.,catalyst poisons) which could otherwise poison the second alkylationcatalyst are removed from the feed stream in the first alkylationreaction zone by the first alkylation catalyst at the same time as thealkylatable aromatic compound is alkylated with alkylating agent.

In operation of another embodiment (e.g., non-reactive guard bed), theprocess for producing alkylated aromatic compounds, for examplemono-alkylated and poly-alkylated aromatic compounds, such processcomprises the steps of: (a) supplying a feed stream to a dehydrationzone, said feed stream comprising an alkylatable aromatic compound,water, and impurities, wherein said impurities comprise a compoundhaving at least one of the following elements: nitrogen, halogens,oxygen, sulfur, arsenic, selenium, tellurium, phosphorus, and Group 1through Group 12 metals; (b) removing at least a portion of said waterfrom said feed stream in said dehydration zone to produce a dehydratedstream comprising said alkylatable aromatic compound, any remainingwater, and said impurities; (c) contacting at least a portion of saiddehydrated stream with a first catalyst having a first poison capacityin a first reaction zone under suitable at least partially liquid phasefirst reaction conditions to remove at least a portion of saidimpurities, and produce an alkylatable aromatic stream having a reducedamount of impurities comprising said alkylatable aromatic compound, anyremaining water, and any remaining impurities, preferably, wherein saidremaining impurities are reduced by at least 25% as compared to saidimpurities in said dehydrated stream; and (d) contacting saidalkylatable aromatic stream and an alkylating agent stream with analkylation catalyst different from said first catalyst, said alkylationcatalyst having a second poison capacity, in an alkylation reaction zoneunder suitable at least partially liquid phase second reactionconditions to alkylate at least a portion of said unreacted alkylatablearomatic compound with said second alkylating agent stream and produce asecond alkylated stream comprising alkylated aromatic compound(s),unreacted alkylatable aromatic compound, any remaining water, and anyremaining impurities.

In the non-reactive guard bed, the impurities are removed from the feedstream in the first reaction zone by the first catalyst in the absenceof the alkylating agent and there is no alkylation of the alkylatablearomatic compound.

Preferably at least 80%, or at least 70%, or at least 60%, or at least50%, by weight, of said impurities are removed in step (c).

Optionally in step (b), at least a portion of said impurities in saidfeed stream are removed in said dehydration zone. Preferably, theimpurities in said dehydrated stream after step (b) is 10% less, 5% lessor 1% less by weight than the impurities in said feed stream. Morepreferably, the impurities in said dehydrated stream after removing atleast a portion of impurities in the dehydration zone is less than 1000wppb, less than 750 wppb, less than 500 wppb or less than 250 wppb.

In the reactive guard bed, the first poison capacity of said firstalkylation catalyst may be greater than said second poison capacity ofsaid second alkylation catalyst. Preferably, the first poison capacityof said first alkylation catalyst is at least 5%, at least 10%, at least15%, at least 20%, at least 25%, at least 30%, at least 35%, at least40%, at least 45% or at least 50% greater than said second poisoncapacity of said second alkylation catalyst.

In the non-reactive guard bed, the first poison capacity of said firstcatalyst may be greater than said second poison capacity of saidalkylation catalyst. Preferably, the first poison capacity of said firstcatalyst is at least 5%, at least 10%, at least 15%, at least 20%, atleast 25%, at least 30%, at least 35%, at least 40%, at least 45% or atleast 50% greater than said second poison capacity of said alkylationcatalyst.

In the reactive guard bed, the portion of said alkylated aromaticcompound that is alkylated with alkylating agent in step (c) is at least1%, at least 2%, at least 5%, at least 7%, at least 10%, at least 13% orat least 15% of said alkylatable aromatic compound.

In the reactive guard bed, the flow rate of said second alkylating agentstream may be greater than the flow rate of said first alkylating agentstream. Preferably, the flow rate of said second alkylating agent streamis at least 5%, at least 10%, at least 15%, at least 20%, at least 25%,at least 30%, at least 35%, at least 40%, at least 45% or at least 50%greater than the flow rate of said first alkylating agent stream.

In some embodiments, prior to step (c) said dehydrated stream is fed toa treatment zone containing a treatment material, and then saiddehydrated stream is contacted with said treatment material in saidtreatment zone under suitable treatment conditions to remove at least aportion of said remaining amount of impurities and to produce said firstalkylated stream. In these embodiments, the amount of impurities aftercontact with said treatment material is 1% less, 5% less, 10% less or15% less by weight than is said dehydrated stream.

In other embodiments, prior to step (a) said feed stream is fed to atreatment zone containing a treatment material, and then said feedstream is contacted with said treatment material in said treatment zoneunder suitable treatment conditions to remove at least a portion of saidimpurities. Preferably, the amount of impurities after treatment is 1%less, 5% less, 10% less or 15% less by weight than is said feed stream.In these embodiments, the treatment material is selected from the groupconsisting of clay, resin, activated alumina, Linde type X, Linde typeA, and combinations thereof.

In the reactive guard bed, said first alkylation catalyst is a largepore molecular sieve having a Constraint Index of less than 2. Suchlarge pore molecular sieve is selected from the group of consisting ofzeolite beta, faujasite, zeolite Y, Ultrastable Y (USY), Dealuminized Y(Deal Y), Rare Earth Y (REY), Ultrahydrophobic Y (UHP-Y), mordenite,TEA-mordenite, ZSM-3, ZSM-4, ZSM-14, ZSM-18, ZSM-20, and combinationsthereof.

In the non-reactive guard bed, said first catalyst is a large poremolecular sieve having a Constraint Index of less than 2. Such largepore molecular sieve is selected from the group of consisting of zeolitebeta, faujasite, zeolite Y, Ultrastable Y (USY), Dealuminized Y (DealY), Rare Earth Y (REY), Ultrahydrophobic Y (UHP-Y), mordenite,TEA-mordenite, ZSM-3, ZSM-4, ZSM-14, ZSM-18, ZSM-20, and combinationsthereof.

The second alkylation catalyst (e.g., reactive guard bed) or thealkylation catalyst (e.g., non-reactive guard bed) is a MCM-22 familymaterial having unit cells of MWW framework topology and characterizedby an X-ray diffraction pattern including d-spacing maxima at 12.4±0.25,3.57±0.07 and 3.42±0.07 Angstroms. Such MCM-22 family material isselected from the group consisting of ERB-1, ITQ-1, ITQ-2, ITQ-30,PSH-3, SSZ-25, MCM-22, MCM-36, MCM-49, MCM-56, UZM-8, EMM-10, EMM-10P,EMM-12, EMM-13 and mixtures thereof.

After removing at least a portion of water in the dehydration zone, thewater in said dehydrated stream is less than 100 wppm, less than 50wppm, less than 25 wppm or less than 10 wppm based on said dehydratedstream.

The water is removed, for example, via distillation, adsorption,evaporation, extraction or flashing. The dehydration zone is adistillation column, a benzene column or a lights column.

After removing additional impurities in said first alkylation zone orsaid first reaction zone, the amount of impurities in said firstalkylated stream is 25% less, 20% less, 15% less, 10% less or 5% lessbased on the weight of said feed stream. Preferably, the amount ofimpurities in said first alkylated stream after removing additionalimpurities in said first alkylation zone is less than 100 wppb, 75 wppb,50 wppb or 25 wppb.

The impurities in said second alkylated stream is 10% less, 5% less or1% less by weight than the impurities in said first alkylated stream.Preferably, the impurities in said second alkylated stream is less than1 wppm, less than 5 wppm, less than 10 wppm, less than 15 wppm, lessthan 20 wppm or less than 25 wppm.

In some embodiments, the alkylation reaction zone(s) are preferablylocated in a single reactor vessel. Alternatively, said first alkylationreaction zone may be located in a separate vessel and may operate as areactive guard bed. Said first reaction zone may be located in aseparate vessel and may operate as a non-reactive guard bed. Thecatalyst in the reactive or non-reactive guard bed is subject to morefrequent regeneration and/or replacement than the second alkylationcatalyst, and hence it is typically provided with a by-pass circuit sothat the alkylation feed(s) may be fed directly to the series connectedreaction zones in the reactor while the guard bed is out of service.

Preferably the by-passable reactive guard bed is located upstream fromthe second alkylation zone. The by-passable non-reactive guard bed islocated upstream from the alkylation zone. Such guard beds may beoperated in co-current upflow or downflow operation. The reactive ornon-reactive guard bed is maintained under suitable at least partialliquid phase conditions.

In the reactive guard bed, at least a portion of the alkylatablearomatic compound and at least a portion of the alkylating agent arepassed through the reactive guard bed prior to entry into the secondalkylation reaction zone.

In the non-reactive guard bed, the alkylatable aromatic compound ispassed through the non-reactive guard bed prior to entry into thealkylation reaction zone.

The catalyst composition used in the reactive guard bed or thenon-reactive guard bed is different from the catalyst composition usedin the second and subsequent alkylation reaction zone(s). The catalystcomposition used in the reactive guard bed or the non-reactive guard bedmay have multiple catalyst compositions (e.g., a mixture of mordeniteand zeolite Y, or a mixture of zeolite beta and zeolite Y). The reactiveguard bed and normally each alkylation reaction zone, is maintainedunder conditions effective to cause alkylation of the alkylatablearomatic compound with the alkylating agent in the presence of analkylation.

In other embodiments, said dehydrated stream further comprises at leasta portion of an overhead stream from a distillation zone.

In another embodiment, said dehydrated stream is cooled to condense atleast a portion of said dehydrated stream to remove at least a portionof any remaining water and impurities.

In another embodiment, the process further comprises the step ofsupplying said dehydrated stream to a distillation zone to remove saidat least a portion of any remaining water before contacting step (c).

In another embodiment, the process further comprises the step ofcombining said dehydrated stream with a stream from a distillation zoneto remove at least a portion of any said remaining water beforecontacting step (c), said distillation zone is a distillation column, abenzene column or a lights column.

The process of claim 1, further comprising the step of supplying asreflux to a distillation column at least a portion of said dehydratedstream from said dehydration zone.

In some embodiments, said alkylatable aromatic compound is benzene. Saidfirst alkylating agent stream or said second alkylating agent streamcomprises an olefin. Optionally, said first or second alkylating agentstream comprises only alkylating agent and impurities, or onlyalkylating agent and water, or a mixture of alkylating agent andimpurities and water.

Said alkylated aromatic compound is a mono-alkylated aromatic compoundin some embodiments. In such case, said alkylating agent is ethylene andsaid mono-alkylated aromatic compound is ethylbenzene, or saidalkylating agent is propylene and said mono-alkylated aromatic compoundis cumene, or said alkylating agent is butylene, and said mono-alkylatedaromatic compound is sec-butyl benzene.

In some embodiments of the process, a mono-alkylated aromatic compoundstream, and optionally said poly-alkylated compound stream, is separatedfrom said second alkylated stream.

Said alkylated aromatic compound is a poly-alkylated aromatic compound,wherein the process further comprises the step of contacting saidpoly-alkylated aromatic compound of step (e) with a transalkylationcatalyst in a transalkylation reaction zone under suitabletransalkylation conditions to produce an additional amount of saidmono-alkylated aromatic compound.

In another embodiment, said transalkylation catalyst is a large poremolecular sieve having a Constraint Index of less than 2.

In another embodiment, said large pore molecular sieve is selected fromthe group of consisting of zeolite beta, faujasite, zeolite Y,Ultrastable Y (USY), Dealuminized Y (Deal Y), Rare Earth Y, mordenite,TEA-mordenite, ZSM-3, ZSM-4, ZSM-18, ZSM-20 and combinations thereof.

The alkylation reactor used in the process of the present disclosure maybe highly selective to the desired mono-alkylated aromatic compound,such as ethylbenzene, but typically produces at least somepoly-alkylated species. The effluent from the final alkylation reactionzone may be subjected to a separation step to recover mono-alkylated andpolyalkylated aromatic compounds. At least a portion of thepoly-alkylated aromatic compound may be supplied to a transalkylationreactor which may be separate from the alkylation reactor. In thetransalkylation reactor, the poly-alkylated aromatic compound is reactedwith the alkylatable aromatic compound to produce an effluent whichcontains additional mono-alkylated aromatic compound. At least a portionof these effluents may be separated to recover the alkylated aromaticcompound (mono-alkylated aromatic compound and/or poly-alkylatedaromatic compound).

One or more embodiments of this disclosure are illustrated in FIGS. 1 to8.

FIG. 1 shows a process 50 for producing an alkylated aromatic compound,for example, a mono-alkylated aromatic compound, such as ethylbenzene,in which a feed stream 1, comprising an alkylatable aromatic compound,water and impurities, is fed to treaters 2 having a treatment zone 2 acontaining a treatment material 4 where it is treated under suitabletreatment conditions to remove a first portion of said impurities,referenced above, and to produce a treater effluent stream 5.Optionally, the treater effluent stream 5 may be heated or cooled inheat exchanger 12 a.

The treater effluent stream 5 is then fed to a dehydration zone 14, suchas a lights removal distillation column, where at least a portion ofsaid water, and optionally a second portion of said impurities areremoved from treater effluent stream 5 to produce a dehydrated stream 13comprising said alkylatable aromatic compound, any remaining amount ofwater and said impurities.

The dehydrated stream 13 is fed to accumulator 16 of distillation zone18. Distillation zone 18 may be a benzene distillation column. Inaccumulator 16, dehydrated stream 13 is combined with the overheadstream 15 from distillation zone 18 (which is cooled by a heat exchanger12 c) to produce an accumulator effluent 17. A portion of accumulatoreffluent 17 is fed as reflux 19 to distillation zone 18. Vapors 24 fromaccumulator 16 are fed to dehydration zone 14 for further separation.Stream 21, the remaining portion of accumulator effluent 17, forms analkylatable aromatic feed stream 41 to alkylator 20, and a alkylatablearomatic feed stream 39 to transalkylator 30. Optionally, stream 21 maybe heated or cooled in heat exchanger 12 b. Heavier compounds (e.g.,poly-alkylated aromatic compounds) are removed as a bottoms stream 22 ofdistillation zone 18 and separated in downstream separation equipment(not shown) to produce a mono-alkylated aromatic compound, such asethylbenzene, and polyalkylated aromatic compounds, such aspolyalkylated feed stream 39 a, discussed below.

Alkylator 20 has at least a first alkylation zone 20 a which contains afirst alkylation catalyst 26 located upstream of and in fluidcommunication with at least a second alkylation zone 20 b which containsa second alkylation catalyst 28. In some embodiments, there is aplurality of series-connected alkylation zones. The first alkylationcatalyst has a first poison capacity and the second alkylation catalysthas a second poison capacity, wherein the first poison capacity isgreater than the second poison capacity. In this embodiment, the firstalkylation reaction zone is a reactive guard bed that is integral withinalkylator 20.

The first alkylation catalyst 26 comprises a large pore molecular sievehaving a Constraint Index of less than 2. In some embodiments, thesecond alkylation catalyst comprises a MCM-22 family molecular sieve,referenced above. In other embodiments, the second alkylation catalystcomprises a medium pore molecular sieve having a Constraint Index of2-12.

In the first alkylation zone 20 a, the alkylatable aromatic feed stream41 to the alkylator and a portion of first alkylating agent stream 43are contacted with the first alkylation catalyst 26 in the firstalkylation reaction zone under suitable at least partially liquid phasefirst reaction conditions. At least a portion, by weight, of saidimpurities are removed, and at least a portion, by weight, of saidalkylatable aromatic compound is alkylated with said first alkylatingagent stream 43, to produce a first alkylated stream comprisingalkylated aromatic compound(s), unreacted alkylatable aromatic compound,any remaining water, and any remaining impurities.

The first alkylated stream is contacted with another portion of saidalkylating agent 43 in the presence of a second alkylation catalyst 28(different from said first alkylation catalyst) in a second alkylationreaction zone 20 b under suitable at least partially liquid phase secondreaction conditions. Said unreacted alkylatable aromatic compound isalkylated with said second alkylating agent stream, to produce a secondalkylated stream comprising additional said alkylated aromaticcompound(s), any remaining water, and any remaining impurities. Thefirst and second alkylated streams, and subsequent alkylation zones, ifany, combine to form an alkylated effluent 45 comprising unreactedalkylatable aromatic compound, any remaining water, and mono-alkylatedand poly-alkylated aromatic compounds. Unlikely, but possible there issome residual alkylation agent present.

The alkylatable aromatic feed stream 39 to the transalkylator,comprising the alkylatable aromatic compound, and the polyalkylated feedstream 39 a (comprising the poly-alkylated aromatic compound from thedownstream separation equipment (not shown)), are fed to transalkylationzone 30 a of transalkylator 30. Transalkylation zone 30 a has at leastone transalkylation catalyst 34. In some embodiments, thetransalkylation catalyst 34 is a large pore molecular sieve having aConstraint Index of less than 2.

In transalkylation zone 30 a, the poly-alkylated aromatic compound inthe polyalkylated feed stream 39 a is contacted with the transalkylatoralkylatable aromatic feed stream 39 in the presence of transalkylationcatalyst 34 under suitable at least partially liquid phasetransalkylation conditions, to produce additional said mono-alkylatedaromatic compound in transalkylator effluent 47.

The alkylated effluent 45, optionally combined with transalkylatoreffluent 47, are fed as distillation feed stream 49 to distillation zone18, to separate the mono-alkylated compounds from said poly-alkylatedcompounds and heavier compounds.

FIGS. 2-4 show alternative embodiments of the use of dehydrated stream13 in the distillation zone 18 of process 50 for producing amono-alkylated aromatic compound of FIG. 1. The pieces of equipment andstreams with the same numerals as in FIG. 1 are the same. In theembodiment of FIG. 2, the dehydrated stream 13, along with reflux 19,are fed to the distillation zone 18. Overhead stream 15 is cooled inheat exchanger 12 c and then flows into accumulator 16. Stream 17, whichcomprises the alkylatable aromatic stream, flows from accumulator 16. Aportion of stream 17 is split off and feed as the reflux 19, referencedabove, to distillation zone 18. As in FIG. 1, stream 21, the remainingportion of stream 17, forms the transalkyator alkylatable aromatic feedstream 39 to transalkylator 30, and the alkylatable aromatic feed stream41 to alkylator 20.

In the embodiment of FIG. 3, the dehydrated stream 13 is combined withthe overhead stream 15 from distillation zone 18 and then cooled in heatexchanger 12 c to form stream 23 which is then fed to accumulator 16.Stream 25, comprising the alkylatable aromatic compound, flows fromaccumulator 16 and is split into reflux stream 27 and stream 29. Stream29, the remaining portion of stream 25, forms the transalkyatoralkylatable aromatic feed stream 39 to transalkylator 30, and thealkylatable aromatic feed stream 41 to alkylator 20.

In the embodiment of FIG. 4, the overhead stream 15 of distillation zone18 flows into accumulator 16 to form stream 17 as in FIG. 1. In thisembodiment, the dehydrated stream 13 is combined with reflux stream 19to form combined reflux stream 33 to distillation zone 18. Stream 35,the remaining portion of stream 17, forms the transalkyator alkylatablearomatic feed stream 39 to transalkylator 30, and the alkylatablearomatic feed stream 41 to alkylator 20. Optionally, stream 35 may beheated or cooled in a heat exchanger 12 b.

FIG. 5 shows a process 100 for producing a mono-alkylated aromaticcompound 100, such as ethylbenzene, using a guard bed in a separatevessel, and which is operated in a reactive mode or a non-reactive mode.When the guard bed is operated in non-reactive mode, no alkylating agentis fed. When the guard bed is operated in reactive mode, it receives aportion of an alkylation agent.

Feed stream 101, comprising an alkylatable aromatic compound, water andimpurities are fed to dehydration zone 14, such as a lights removaldistillation column. The pieces of equipment and streams with the samenumerals as in FIG. 1 are the same. In dehydration zone 14, at least aportion of said water, and optionally a portion of said impurities areremoved from the feed stream 101 to produce a dehydrated stream 109comprising said alkylatable aromatic compound, any remaining amount ofsaid impurities and any remaining water. The dehydrated stream 109 isfed to a treatment zone 102 containing a treatment material 102 a whereit is treated under suitable treatment conditions to remove additionalsaid impurities and to produce effluent stream 111. The impurities andtreatment material 102 a are the same as those described above.Optionally, the effluent stream 111 may be heated or cooled in a heatexchanger (not shown).

Effluent stream 111 is fed to accumulator 16 of distillation zone 18,where it is combined with the overhead stream 115 from distillation zone18 to produce a combined effluent 117. Distillation zone 18 may be abenzene distillation column. A portion of combined effluent 117 is fedas reflux 119 to distillation zone 18. Vapors 124 from accumulator 16are fed to dehydration zone 14 for further separation. Stream 121, theremaining portion of combined effluent 117, may be heated or cooled in aheat exchanger 12 d. Also, stream 121 forms an alkylatable aromatic feedstream 139 to transalkylator 30, and an alkylatable aromatic feed stream141 to (reactive or non-reactive) guard bed 22. Heavier compounds (e.g.,poly-alkylated aromatic compounds) are removed as a bottoms stream 122of distillation zone 18 and separated in downstream separation equipment(not shown) to produce an alkylated aromatic compound, such asethylbenzene, and polyalkylated aromatic compounds, such aspolyalkylated feed stream 139 a, discussed below.

Guard bed 22 is separate from alkylator 20 and located upstream of andis in fluid communication with at least a second alkylation zone 20 b.When guard bed 22 is a reactive guard bed, it is the first alkylationzone and contains a first alkylation catalyst 26. When guard bed 22 is anon-reactive guard bed, is not an alkylation zone because no alkylatingagent is fed.

Second alkylation zone 20 b contains a second alkylation catalyst 28.The first alkylation catalyst has a first poison capacity and isdifferent from the second alkylation catalyst which has a second poisoncapacity. The first poison capacity is greater than the second poisoncapacity. Preferably, the first alkylation catalyst 26 comprises a largepore molecular sieve having a Constraint Index of less than 2.

In some embodiments, the second alkylation catalyst comprises a MCM-22family molecular sieve, referenced above. In other embodiments, thesecond alkylation catalyst comprises a medium pore molecular sievehaving a Constraint Index of 2-12.

When guard bed 22 is a reactive guard bed, the alkylatable aromatic feedstream 141 and a portion of alkylating agent stream 143 are contacted inthe presence of the first alkylation catalyst 26, under at least partialliquid phase condition, to form the first alkylated stream whichcomprises comprising alkylated aromatic compound(s), unreactedalkylatable aromatic compound, any remaining water, and any remainingimpurities.

When guard bed 22 is a non-reactive guard bed, it receives thealkylatable aromatic feed stream 141 which is contacted with the firstalkylation catalyst 26 (in the absence of alkylating agent) undersuitable at least partially liquid phase first reaction conditions toremove at least a portion, by weight, of said impurities, and produce analkylatable aromatic stream comprising said alkylatable aromaticcompound, any remaining water, and any remaining impurities.

The first alkylated stream or the alkylatable aromatic stream is thenfed to second alkylation zone 20 b and contacted with additionalalkylating agent stream 143 in the presence of second alkylationcatalyst 28, under suitable at least partially liquid phase secondreaction conditions, to produce a second alkylated stream whichcomprises additional amounts of alkylated aromatic compounds.

The first and second alkylated streams, and subsequent alkylation zones,if any, combine to form an alkylated effluent 145 comprising analkylated aromatic compound, unreacted alkylatable aromatic compound,any remaining water, and any remaining impurities.

The transalkylator alkylatable aromatic feed stream 139, comprising thealkylatable aromatic compound, and polyalkylated aromatic feed stream139 a, comprising the poly-alkylated aromatic compound, are fed totransalkylation zone 30 a. Transalkylation zone 30 a has at least onetransalkylation catalyst 34. In some embodiments, transalkylationcatalyst 34 is a large pore molecular sieve having a Constraint Index ofless than 2.

In transalkylation zone 30 a, the poly-alkylated aromatic feed stream139 a is contacted with transakylator alkylatable aromatic feed stream139 in the presence of transalkylation catalyst 34 under suitable atleast partially liquid phase transalkylation conditions to produceadditional said mono-alkylated aromatic compound in transalkylatoreffluent 147.

The alkylated effluent 145, optionally combined with transalkylatoreffluent 147, are fed as distillation feed stream 149 to distillationzone 18, to separate the mono-alkylated compounds from saidpoly-alkylated compounds and heavier compounds. The polyalkylated andheavier compounds are separated in downstream separation equipment (notshown).

FIGS. 6-8 show alternative embodiments of the use of effluent stream 111(which comprises dehydrated stream 109) in distillation zone 18 ofprocess 100 for producing a mono-alkylated aromatic compound of FIG. 5.The pieces of equipment and streams with the same numerals as in FIG. 5are the same. In the embodiment of FIG. 6, the effluent stream 111 alongwith reflux stream 119 is fed to the distillation zone 18. Overheadstream 115 of distillation zone 18 flows into accumulator 16. Stream117, which comprises the alkylatable aromatic stream, flows fromaccumulator 16. A portion of stream 117 is split off and fed as reflux19 to distillation zone 18. Stream 121, the remaining portion of stream117, forms the transalkylator feed stream 139 to transalkylator 30, andthe alkylator feed stream 141 to guard bed 22, as in FIG. 5. Optionally,stream 121 may be heated or cooled in heat exchanger 12 d.

In the embodiment of FIG. 7, the effluent stream 111 is combined withthe overhead stream 115 from distillation zone 18 and then cooled inheat exchanger 12 c to form stream 123 which is then fed to accumulator16. Stream 125, comprising the alkylated aromatic compound, flows fromaccumulator 16. This stream 16 is split into reflux stream 127 andstream 129. Stream 129, the remaining portion of stream 125, forms thetransalkylator alkylatable aromatic feed stream 139 to transalkylator30, and the alkylatable aromatic feed stream 141 to guard bed 22.Optionally, stream 129 may be heated or cooled in a heat exchanger 12 d.

In the embodiment of FIG. 8, the overhead stream 115 flows intoaccumulator 16 to form stream 117 and reflux stream 119 as in FIG. 5. Inthis embodiment, the effluent stream 111 is combined with stream 119that is split off of stream 17 to form reflux stream 133 to distillationzone 18. Stream 135, the remaining portion of stream 117, forms thetransalkylator alkylatable aromatic feed stream 139 to transalkylator30, and the alkylatable aromatic feed stream 141 to guard bed 22.Optionally, stream 135 may be heated or cooled in a heat exchanger 12 d.

The disclosure will now be more particularly described with reference tothe following Examples.

Examples 1-6 Measurement of Poison Capacity

In Examples 1-6, the poison capacity for collidine was determined byfeeding collidine in the gas phase in which its uptake was recorded viathermogravimetric analyzer. The total uptake is one measure of azeolite's capacity for adsorbing nitrogen-containing compounds.

TABLE 1 Approximate Poison Zeolite Content Capacity Example Catalyst (%)(meq/g) 1 MWW 80 80-130 (Comparative) (MCM-49) 2 Beta 80 701 (Non-MWW) 3USY 80 925 (Non-MWW) 4 ZSM-12 65 531 (Non-MWW) 5 Mordenite 65 385(Non-MWW) 6 Solid Phosphoric None 501 Acid (Non-MWW)

As can been seen, Table 1 shows that the poison capacity using collidinefor a catalyst having MWW topology is much less than that for catalysthaving non-MWW topology.

Examples 7 and 8

In Examples 7 and 8, the capacity of an MWW and zeolite beta catalyststo absorb an N-formyl morpholine (NFM) impurity was determined. Twoalkylation reactors were placed in series with an NFMimpurity-containing benzene feed supplied to a first alkylation reactorhaving first alkylation catalyst (Rx 1). The effluent of Rx 1 was thefeed to a second alkylation reactor having a second alkylation catalyst(Rx 2). Rx1 and Rx2 each reactor had a separate ethylene injectionpoints and this configuration is like the first two stages of amulti-stage series-connected alkylation reactor. For these experimentsRx 1 was a reactive guard bed and was the first reaction zone in analkylation reactor. Deactivation of Rx 2 was used to indicate when Rx 1has achieved its maximum poison capacity and catalyst poisons were nolonger completely retained by Rx 1. NFM was fed at a concentration of0.3 wt wppm based on the weight of the benzene feed.

The NFM absorption capacities in the Examples are calculated from thetime on stream and the time at which deactivation is observed in Rx 2.

TABLE 2 NFM Absorption Zeolite for Rx1 Zeolite for Rx2 Capacity (wppm(80 wt. % zeolite (80 wt. % zeolite based on the content based oncontent based on weight of the Example weight of zeolite) weight ofzeolite) zeolite) 7 MWW MWW 900-1000 (Comparative) 8 Beta MWW 5950

As can been seen, Table 2 shows that the NFM absorption capacity forzeolite beta as the first catalyst is superior to a first catalystcomprising an MWW catalyst.

All patents, patent applications, test procedures, priority documents,articles, publications, manuals, and other documents cited herein arefully incorporated by reference to the extent such disclosure is notinconsistent with this disclosure and for all jurisdictions in whichsuch incorporation is permitted.

When numerical lower limits and numerical upper limits are listedherein, ranges from any lower limit to any upper limit are contemplated.

While the illustrative embodiments of the disclosure have been describedwith particularity, it will be understood that various othermodifications will be apparent to and can be readily made by thoseskilled in the art without departing from the spirit and scope of thedisclosure. Accordingly, it is not intended that the scope of the claimsappended hereto be limited to the examples and descriptions set forthherein but rather that the claims be construed as encompassing all thefeatures of patentable novelty which reside in the present disclosure,including all features which would be treated as equivalents thereof bythose skilled in the art to which the disclosure pertains.

1. A process for producing an alkylated aromatic compound, said processcomprising the steps of: (a) supplying a feed stream to a dehydrationzone, said feed stream comprising an alkylatable aromatic compound,water, and impurities, wherein said impurities comprise a compoundhaving at least one of the following elements: nitrogen, halogens,oxygen, sulfur, arsenic, selenium, tellurium, phosphorus, and Group 1through Group 12 metals; (b) removing at least a portion of said waterfrom said feed stream in said dehydration zone operated under suitabledehydration conditions to produce a dehydrated stream comprising saidalkylatable aromatic compound, any remaining water, and said impurities;(c) contacting at least a portion of said dehydrated stream and a firstalkylating agent stream with a first alkylation catalyst having a firstpoison capacity in a first alkylation reaction zone under suitable atleast partially liquid phase first reaction conditions to remove atleast a portion of said impurities, and to alkylate at least a portionof said alkylatable aromatic compound with said first alkylating agentstream and produce a first alkylated stream comprising alkylatedaromatic compound(s), unreacted alkylatable aromatic compound, anyremaining water, and any remaining impurities; and (d) contacting saidfirst alkylated stream and a second alkylating agent stream with asecond alkylation catalyst different from said first alkylationcatalyst, said second alkylation catalyst having a second poisoncapacity in a second alkylation reaction zone under suitable at leastpartially liquid phase second reaction conditions to alkylate at least aportion of said unreacted alkylatable aromatic compound with said secondalkylating agent stream and produce a second alkylated stream comprisingadditional said alkylated aromatic compound(s), unreacted alkylatablearomatic compound, any remaining water, and any remaining impurities. 2.The process of claim 1, wherein in removing step (b) at least a portionof said impurities in said feed stream are removed in said dehydrationzone.
 3. The process of claim 1, wherein in contacting step (c) saidfirst poison capacity of said first alkylation catalyst is greater thansaid second poison capacity of said second alkylation catalyst.
 4. Theprocess of claim 1, wherein prior to step (c) said dehydrated stream isfed to a treatment zone containing a treatment material, and then saiddehydrated stream is contacted with said treatment material in saidtreatment zone under suitable treatment conditions to remove at least aportion of said impurities.
 5. The process of claim 4, wherein saidtreatment material is selected from the group consisting of clay, resin,activated alumina, Linde type X, Linde type A, and combinations thereof.6. The process of claim 1, wherein prior to step (a) said feed stream isfed to a treatment zone containing a treatment material, and then saidfeed stream is contacted with said treatment material in said treatmentzone under suitable treatment conditions to remove at least a portion ofsaid impurities.
 7. The process of claim 6, wherein said treatmentmaterial is selected from the group consisting of clay, resin, activatedalumina, Linde type X, Linde type A, and combinations thereof.
 8. Theprocess of claim 1, wherein said first alkylation catalyst is a largepore molecular sieve having a Constraint Index of less than
 2. 9. Theprocess of claim 8, wherein said large pore molecular sieve is selectedfrom the group of consisting of zeolite beta, faujasite, zeolite Y,Ultrastable Y (USY), Dealuminized Y (Deal Y), Rare Earth Y (REY),Ultrahydrophobic Y (UHP-Y), mordenite, TEA-mordenite, ZSM-3, ZSM-4,ZSM-14, ZSM-18, ZSM-20, and combinations thereof.
 10. The process ofclaim 1, wherein said second alkylation catalyst is a MCM-22 familymaterial having unit cells of MWW framework topology and characterizedby an X-ray diffraction pattern including d-spacing maxima at 12.4±0.25,3.57±0.07 and 3.42±0.07 Angstroms.
 11. The process of claim 10, whereinsaid MCM-22 family material is selected from the group consisting ofERB-1, ITQ-1, ITQ-2, ITQ-30, PSH-3, SSZ-25, MCM-22, MCM-36, MCM-49,MCM-56, UZM-8, EMM-10, EMM-10P, EMM-12, EMM-13 and mixtures thereof. 12.The process of claim 1, wherein said impurities in said second alkylatedstream from said second alkylation zone are 10% less than saidimpurities in said first alkylated stream.
 13. The process of claim 4,wherein after contact with said treatment material said impurities insaid dehydrated stream are 10% less than before treatment.
 14. Theprocess of claim 6, wherein after contact with said treatment materialsaid impurities in said feed stream are 10% less than before treatment.15. The process of claim 1, wherein said first alkylation reaction zoneis upstream of said second alkylation reaction zone.
 16. The process ofclaim 1, wherein said first alkylation reaction zone is in a separatevessel from said second alkylation reaction zone.
 17. The process ofclaim 1, further comprising the step of combining said dehydrated streamfrom said dehydration zone with a stream from a distillation zone toremove said remaining water before contacting step (c).
 18. The processof claim 1, wherein said dehydrated stream from said dehydration zonefurther comprises at least a portion of an overhead stream from adistillation zone.
 19. The process of claim 1, further comprising thestep of supplying as reflux to a distillation column at least a portionof said dehydrated stream from said dehydration zone.
 20. The process ofclaim 1, wherein said dehydrated stream from said dehydration zone iscooled to condense to remove additional amounts of any remaining wateror impurities.
 21. The process of claim 1, wherein said alkylatablearomatic compound is benzene.
 22. The process of claim 1, wherein saidfirst alkylating agent stream comprises an olefin and said impurities orsaid second alkylating agent stream comprises an olefin and saidimpurities, and wherein at least a portion of said impurities areremoved in step (c).
 23. The process of claim 1, wherein said alkylatingagent is ethylene and said mono-alkylated aromatic compound isethylbenzene, or said alkylating agent is propylene and saidmono-alkylated aromatic compound is cumene, or said alkylating agent isbutylene and said mono-alkylated aromatic compound is sec-butyl benzene.24. The process of claim 1, wherein said alkylated aromatic compound(s)comprises mono-alkylated aromatic compounds and poly-alkylated aromaticcompounds.
 25. The process of claim 24, wherein said process furthercomprising the step of: (e) separating a mono-alkylated aromaticcompound stream from said second alkylated stream.
 26. The process ofclaim 25, further comprising the step of: (f) separating apoly-alkylated compound stream from said second alkylated stream. 27.The process of claim 26, further comprising the step of: (g) contactingsaid poly-alkylated aromatic compound stream and another portion of saidfeed stream with a transalkylation catalyst in a transalkylationreaction zone under suitable at least partially liquid phasetransalkylation conditions to transalkylate said poly-alkylated aromaticcompound stream and produce additional said mono-alkylated aromaticcompound.
 28. The process of claim 27, wherein said transalkylationcatalyst is a large pore molecular sieve having a Constraint Index ofless than
 2. 29. The process of claim 28, wherein said large poremolecular sieve is selected from the group of consisting of zeolitebeta, faujasite, zeolite Y, Ultrastable Y (USY), Dealuminized Y (DealY), Rare Earth Y(REY), Ultrahydrophobic Y (UHP-Y), mordenite,TEA-mordenite, ZSM-3, ZSM-4, ZSM-14, ZSM-18, ZSM-20 and combinationsthereof.
 30. A process for producing an alkylated aromatic compound,said process comprising the steps of: (a) supplying a feed stream to adehydration zone, said feed stream comprising an alkylatable aromaticcompound, water, and impurities, wherein said impurities comprise acompound having at least one of the following elements: nitrogen,halogens, oxygen, sulfur, arsenic, selenium, tellurium, phosphorus, andGroup 1 through Group 12 metals; (b) removing at least a portion of saidwater from said feed stream in said dehydration zone operated undersuitable dehydration conditions to produce a dehydrated streamcomprising said alkylatable aromatic compound, any remaining water, andsaid impurities; (c) contacting at least a portion of said dehydratedstream with a first catalyst having a first poison capacity in a firstreaction zone under suitable at least partially liquid phase firstreaction conditions to remove at least a portion of said impurities, andproduce an alkylatable aromatic stream having a reduced amount ofimpurities comprising said alkylatable aromatic compound, any remainingwater, and any remaining impurities; and (d) contacting said alkylatablearomatic stream of step (c) and an alkylating agent stream with analkylation catalyst different from said first catalyst, said alkylationcatalyst having a second poison capacity greater than said first poisoncapacity, in an alkylation reaction zone under suitable at leastpartially liquid phase second reaction conditions to alkylate at least aportion of said unreacted alkylatable aromatic compound with saidalkylating agent stream and produce an alkylated stream comprisingalkylated aromatic compound(s), unreacted alkylatable aromatic compound,any remaining water, and any remaining impurities.
 31. The process ofclaim 30, wherein in removing step (b) at least a portion of saidimpurities in said feed stream are removed in said dehydration zone. 32.The process of claim 30, wherein prior to step (c) said dehydratedstream is fed to a treatment zone containing a treatment material, andthen said dehydrated stream is contacted with said treatment material insaid treatment zone under suitable treatment conditions to remove atleast a portion of said impurities.
 33. The process of claim 32, whereinsaid treatment material is selected from the group consisting of clay,resin, activated alumina, Linde type X, Linde type A, and combinationsthereof.
 34. The process of claim 30, wherein prior to step (a) saidfeed stream is fed to a treatment zone containing a treatment material,and then said feed stream is contacted with said treatment material insaid treatment zone under suitable treatment conditions to remove atleast a portion of said impurities.
 35. The process of claim 34, whereinsaid treatment material is selected from the group consisting of clay,resin, activated alumina, Linde type X, Linde type A, and combinationsthereof.
 36. The process of claim 30, wherein said first catalyst is alarge pore molecular sieve having a Constraint Index of less than
 2. 37.The process of claim 36, wherein said large pore molecular sieve isselected from the group of consisting of zeolite beta, faujasite,zeolite Y, Ultrastable Y (USY), Dealuminized Y (Deal Y), Rare Earth Y(REY), Ultrahydrophobic Y (UHP-Y), mordenite, TEA-mordenite, ZSM-3,ZSM-4, ZSM-14, ZSM-18, ZSM-20, and combinations thereof.
 38. The processof claim 30, wherein said alkylation catalyst is a MCM-22 familymaterial having unit cells of MWW framework topology and characterizedby an X-ray diffraction pattern including d-spacing maxima at 12.4±0.25,3.57±0.07 and 3.42±0.07 Angstroms.
 39. The process of claim 38, whereinsaid MCM-22 family material is selected from the group consisting ofERB-1, ITQ-1, ITQ-2, ITQ-30, PSH-3, SSZ-25, MCM-22, MCM-36, MCM-49,MCM-56, UZM-8, EMM-10, EMM-10P, EMM-12, EMM-13 and mixtures thereof. 40.The process of claim 30, wherein said first reaction zone is in aseparate vessel from said alkylation reaction zone.
 41. The process ofclaim 30, wherein the first reaction zone is in the same vessel as saidalkylation reaction zone.
 42. The process of claim 30, furthercomprising the step of combining said dehydrated stream from saiddehydration zone with a stream from a distillation zone to remove saidremaining water before contacting step (c).
 43. The process of claim 30,further comprising the step of supplying said dehydrated stream fromsaid dehydration zone to a distillation zone to remove said anyremaining water before contacting step (c), said distillation zone is adistillation column, a benzene column or a lights column.
 44. Theprocess of claim 30, wherein said dehydrated stream from saiddehydration zone further comprises at least a portion of an overheadstream from a distillation zone.
 45. The process of claim 30, furthercomprising the step of supplying as reflux to a distillation column atleast a portion of said dehydrated stream from said dehydration zone.46. The process of claim 30, wherein said dehydrated stream from saiddehydration zone is cooled to condense at least a portion of said firstalkylated stream to remove said any remaining water and impurities. 47.The process of claim 30, wherein said alkylatable aromatic compound isbenzene.
 48. The process of claim 30, wherein said alkylating agentstream comprises an olefin and said impurities, and wherein at least aportion of said impurities are removed in step (c).
 49. The process ofclaim 30, wherein said alkylating agent is ethylene and saidmono-alkylated aromatic compound is ethylbenzene, or said alkylatingagent is propylene and said mono-alkylated aromatic compound is cumene,or said alkylating agent is butylene and said mono-alkylated aromaticcompound is sec-butyl benzene.
 50. The process of claim 30, wherein saidalkylated aromatic compound(s) comprises mono-alkylated aromaticcompounds and poly-alkylated aromatic compounds.
 51. The process ofclaim 50, wherein said process further comprising the step of: (e)separating a mono-alkylated aromatic compound stream from said secondalkylated stream.
 52. The process of claim 51, further comprising thestep of: (f) separating a poly-alkylated compound stream from saidsecond alkylated stream.
 53. The process of claim 52, further comprisingthe step of: (g) contacting said poly-alkylated aromatic compound streamand another portion of said dehydrated stream with a transalkylationcatalyst in a transalkylation reaction zone under suitable at leastpartially liquid phase transalkylation conditions to transalkylate saidpoly-alkylated aromatic compound stream and produce additional saidmono-alkylated aromatic compound.
 54. The process of claim 53, whereinsaid transalkylation catalyst is a large pore molecular sieve having aConstraint Index of less than
 2. 55. The process of claim 54, whereinsaid large pore molecular sieve is selected from the group of consistingof zeolite beta, faujasite, zeolite Y, Ultrastable Y (USY), DealuminizedY (Deal Y), Rare Earth Y(REY), Ultrahydrophobic Y (UHP-Y), mordenite,TEA-mordenite, ZSM-3, ZSM-4, ZSM-14, ZSM-18, ZSM-20 and combinationsthereof.